Fluid pressure regulating valves



Oct 15, 1968 K. A. W. KEMP 3,405,640

FLUID PRESSURE REGULATING VALVES Filed Feb. 16, 1967 United States Patent 3,405,640 FLUID PRESSURE REGULATING VALVES Kenneth Albert Walters Kemp, Ealing, England, assignor to C.A.V. Limited, London, England, a British Company Filed Feb. 16, 1967, Ser. No. 616,557 Claims priority, application Great Britain, Mar. 14, 1966, 11,020/ 66 4 Claims. (Cl. 103-5) ABSTRACT OF THE DISCLOSURE A fuel pumping system comprising an injection pump and a charge pump in series and having a fluid pressure regulating valve comprising a pistonmovable within a cylinder by the action of fluid pressure from the outlet of said charge pump and against the action of resilient means, a port which can be uncovered to a drain either by a groove on the piston or by the end of the piston as the latter is moved by the fluid pressure. Said piston moving progressively with increasing pressure against the action of said resilient means to first open, then close, then re-open said port.

This invention relates to fluid pressure regulating valves and has for its object to provide such a valve in a simple and convenient form.

A fluid pressure regulating valve in accordance with the invention comprises in combination, a piston slidable within a cylinder, resilient means biasing the piston towards one end of the cylinder, said piston being arranged to be moved in opposition to the action of the resilient means by the fluid pressure which is to be controlled, a port formed in the wall of said cylinder, said port being arranged to be uncovered to said one end of the cylinder as the piston is moved by the fluid pressure against the action of the resilient means thereby to allow fluid under pressure to escape through said port, and a groove or the equivalent formed in the periphery of said piston intermediate the ends thereof, said groove or the equivalent being in communication with said one end of the cylinder, the arrangement being such that as the fluid pressure increases from zero the port will be closed until the piston has moved a suflicient amount against the action of the resilient means whereupon the port will be open to the groove or the equivalent, and as the pressure further increases the port will be reclosed until it is uncovered by the end of the piston which is exposed to the fluid pressure.

One example of a fluid pressure regulating valve will now be described with reference to the accompanying sectional side elevation which shows the valve and a pump. The valve comprises a body portion having formed therein a stepped cylindrical blind bore 11. The inner and narrower end of the bore is in communication with a fluid inlet 12 whilst the outer end of the bore is in communication with a drain connection 13. Moreover, the outer end of the bore is closed by a plug 14 which is in screw thread engagement with the body part. Within the bore is located a tubular barrel 15 having a pcripheral flange 16 which is maintained in sealing engagement with a step defined in the bore, by the action of a coiled compression spring 17 located intermediate the plug 14 and an abutment piece 18 bearing against the end of the barrel remote from the blind end of the bore 11.

Within the barrel is formed a cylindrical drilling which constitutes a cylinder for a piston 19 slidable therein. The piston is loaded towards the blind end of the bore 11 by a pair of coiled compression springs 20 and 21, positioned one within the other and located on the piston by a projection formed thereon. At its other end the spring 3,405,640 Patented Oct. 15, 1968 20 is located about a peg 22 which is formed integrally with the abutment piece 18 and which extends within the cylinder towards the blind end of the bore. The spring 21 has a shorter free length than the spring 20 and also has a higher rate.

In the wall of the barrel 15 is formed a port 23 which connects the cylinder with the wider end of the bore. The port 23 is arranged to be covered by the piston 19 when the latter is at the position shown. Furthermore, formed in the periphery of the piston intermediate its ends is a circumferential groove 24 which communicate with the narrower end of the bore 11 by way of drillings in the piston.

In use, when fluid under pressure is applied to the narrower end of the bore by way of the inlet 12 the piston 19 will be moved against the action of the springs. Assuming that the fluid pressure increases from zero the port 23 will remain closed until the pressure has increased sufliciently to cause the piston to be moved so that the groove 24 is opened to the port 23. When this occurs fluid will flow through the groove and the port 23 to the drain. Increase in pressure will cause progressive opening of the groove to the port and the flow of liquid to the drain will increase. As the pressure further increases the port will be reclosed by the piston as the groove 24 is moved out of registration with the port and upon a further increase in pressure the port 23 will be reopened by the end of the piston.

One application for such a valve exists in a liquid fuel pumping apparatus for supplying fuel to an internal combustion engine and of the kind which employs a feed pump of the vane type. The feed pump is shown in the drawing and is provided with an outlet 30 which is in communication with the inlet 12 of the valve and the inlet of the pump is connected to the drain 13, the plug 14 being provided with an inlet 31 for liquid fuel. Since the pump is of the constant displacement type the quantity of fuel pumped is proportional to the speed of rotation of the pump and the pressure at the outlet 30 of the pump will be controlled by the valve so that initially it increases very quickly as the speed of rotation of the pump is increased from zero. The pressure will then increase slightly over a given speed range, corresponding to registration of the groove with the port, and then for a small increase in speed the pressure will rise quickly, this occurring whilst the port 23 is reclosed by the piston and then the pressure will increase gradually as the end of the piston reopens the port.

As shown a tubular filter element 25 is located within the bore to filter the fuel from the source to the inlet of the pump by way of the drain 13.

The fact that the spring 21 is shorter than the spring 20 means that it is only brought into action after the piston has moved a predetermined extent. In this way the pressure/speed characteristic of the valve and feed pump can be modified as required. As shown the spring 21 only comes into operation when the end of the piston uncovers the port 23.

The characteristic of valve is used for controlling the supply of excess fuel to the engine for starting purposes. As shown the output 30 of the feed pump is connected to an injection pump 50 by way of a throttle control 51. In order to provide excess fuel an excess fuel valve 52 is provided and this comprises a cylindrical spool 53 having a groove 54 formed in its periphery. The spool is loaded by a compression spring 55 to a position in which communication is established directly between a point upstream of the throttle 51 valve and the injection pump 50 through the groove 54. The end of the spool remote from the spring is subjected to the outlet pressure of the feed pump. The arrangement is such that the spool is not moved against the action of the spring until the output pressure of the feed pump rises sharply when the port 23 is reclosed by the piston as described. A' latch (not shown) is provided to retain the spool in the position in which it is moved by the increase in fuel pressure and this latch must be released when excess fuel is required for starting purposes. 4

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A fluid pressure regulating valve comprising in combination, a piston slidable within a cylinder, resilient means biasing the piston towards one end of the cylinder, said piston :being arranged to be moved in opposition to the action of the resilient means by the fluid pressure which is to be controlled, a port formed in the wall of said cylinder, said port being arranged to be uncovered to said one end of the cylinder as the piston is moved by the fluid pressure against the action of the resilient means thereby to allow fluid under pressure to escape through said port, and a groove or the equivalent formed in the periphery of the said piston intermediate the ends thereof, said groove or the equivalent being in I communication with said one end of the cylinder, the arrange ment being such that as the fluid pressure increases from zero the port will be closed until the piston has moved a sufficient amount against the action of the resilient means whereupon the port will be open to the groove or the equivalent, and as the pressure further increases the port will be reclosed until it is uncovered by the end of the piston which is exposed to the fluid pressure.

2. A fluid pressure regulating valve as claimed in claim 1 in which said resilient means comprises a coiled compression spring.

3. A fluid pressure regulating valve as claimed in claim 2 including a further coiled compression spring which acts upon the piston only after the groove has opened to the 4. A liquid fuel pumping apparatus for supplying fuel to an internal combustion engine and comprising in combination an injection pump for supplying fuel in timed relationship to an engine, a feed pump of the constant displacement type for supplying fuel to the injection pump, a throttle for controlling the quantity of fuel delivaaoae o ered to the injection pump, an excess fuel valve which when open permits fuel to be supplied directly to the in jection pump from the feedv pump, said excess fuel valve being arranged to be closed when the output pressure of the feed pump attains a. predetermined value, and a valve for controlling the output pressure of the feed pump said valve comprising a piston slidable within a cylinder, resilient means biasing the piston towards one end of the cylinder, said piston being arranged to be moved in opposition to the action of the resilient means by the output pressure of the feed pump, a port formed in the wall of said cylinder, said port being arranged to be uncovered to said one end of the cylinder as the piston is moved by against the action of the resilient means thereby to allow fuel under pressure toescape through said port, and a groove or the equivalent formed in the periphery of said piston intermediate the ends thereof, said-groove or the equivalent being in communication with said one end of the cylinder, the arrangement being such that as the fuel pressure increases from zero the port will be closed until the piston has moved a suflicient amount against the action of the resilient means whereupon the port will be open to the groove or the equivalent and as the pressure further increases the port will be reclosed until it is uncovered by the end of the piston thereby resulting in a rapid increase in fuel pressure which opens said excess fuel valve.

References Cited UNITED STATES PATENTS 3,025,797 3/ 1962 Hutcheon.

3,151,567 10/1964 Lawrence 10342 X 3,161,133 12/1964 Hutcheon 103--2 3,291,154 12/1966 Bounds 137624.l8 3,292,546 12/ 1966 Evans.

3,315,701 4/1967 Stilwell l37-624.18 3,351,020 11/1967 Kemp.

3,362,335 1/1968 Stephens et al. 10342 3,363,569 1/1968 Roosa 1035 FRED C. MATTERN, JR., Primary Examiner.

W. J. KRAUSS, Assistant Examiner. 

